Although the magnetoencephalogram (MEG) does not see sources in the brain which are radially-oriented to the skull or are deeply located in the head, it can provide better information about tangential sources in the cortex than does the electroencphalogram (EEG). Tt is proposed to test a method for using this capability of the MEG to clarify the sources of the evoked response. This method consists of four steps. First, MEG and EEG measurements are made; these consist of MEG and EEG maps measured over the scalp (in both monopolar and bipolar form), and MEG curves of falloff in signal strength with distance from the head. Second, MEG maps and falloff curves are used to determine the tangential component of sources which are cortical or near-cortical. Third, EEG maps are computed due to these tangential sources, then subtracted from the experimental EEG maps; the residual maps presumably are due only to cortical, radial sources or to deep, radial and tangential sources. Fourth, these sources are determined from the residual maps. The method will be tested on sources of three evoked signals of present interest. These are the source of the N20 signal of the somatosensory evoked response, the source of the P100 signal of the visual evoked response, and the source of the N100-P200 complex of the auditory evoked response. The tests will determine the effectiveness of the method, and whether or not there are unforeseen problems. As a byproduct of the tests, the clarification of the three sources should help resolve present problems concerning their nature and distribution in the brain.